WO2016199388A1

WO2016199388A1 - Rubber composition for hose, and hose

Info

Publication number: WO2016199388A1
Application number: PCT/JP2016/002700
Authority: WO
Inventors: 常西　洋平
Original assignee: 株式会社ブリヂストン
Priority date: 2015-06-09
Filing date: 2016-06-03
Publication date: 2016-12-15
Also published as: CN107614591A; EP3309208A4; JPWO2016199388A1; US20180142091A1; EP3309208A1

Abstract

Provided is a rubber composition that is for a hose and that can achieve post-vulcanization flexibility as well as dimensional stability during production/extrusion, while also ensuring flame-retardancy. Also provided is a hose. This rubber composition for a hose includes a rubber component, carbon black, and a plasticizing component and is characterized by including 60 parts by mass or more of chloroprene rubber in 100 parts by mass of the rubber component, by comprising more than 50 parts by mass of the carbon black per 100 parts by mass of the rubber component, by the plasticizing component including a flame-retardant plasticizer, and by comprising 2 parts by mass or more of the flame-retardant plasticizer per 100 parts by mass of the rubber component.

Description

Rubber composition for hose and hose

The present invention relates to a rubber composition for a hose and a hose.

Conventionally, studies have been made to improve weather resistance, fatigue resistance, wear resistance, and the like for hydraulic hoses used in construction machines and the like (see, for example, Patent Document 1).
In recent years, the hydraulic hose has been increasingly used in coal mines and mines, and in consideration of safety during work, improvement in flame retardancy is required. Here, the flame retardancy required for the hydraulic hose is mainly defined by, for example, the MSHA standard (US mine safety standard) in the United States.
Also, in recent years, along with the use of ultra-large hydraulic excavators, large-diameter high-pressure hoses are often used in harsher usage environments. Tend to be required.

However, in the conventional flame retardant outer rubber, the outer shell crack may occur after long-term use due to an increase in bending stress due to the large diameter.

In addition, for chloroprene rubber from which vulcanized rubber used for rubber members for automobiles, hoses, rubber molds and vibration-proof rubber can be obtained, the heat resistance is further improved without impairing the mechanical properties, compression set and elongation fatigue properties. (For example, refer to Patent Document 2).
However, a rubber capable of achieving both flexibility after vulcanization and dimensional stability during production extrusion while ensuring flame retardancy has not been obtained, and development of such rubber has been strongly demanded. .

JP 2010-121006 A International Publication No. 2009/035109

Therefore, an object of the present invention is to provide a rubber composition for a hose that can achieve both flexibility after vulcanization and dimensional stability during production extrusion while ensuring flame retardancy. Another object of the present invention is to provide a hose having both flexibility and dimensional stability of the outer diameter of the product while ensuring flame retardancy.

The present inventors (i) based on the increase in filler content by blending a plasticizer and increasing the plasticizer content in a rubber composition having a high filler content such as carbon black. A decrease in elongation (flexibility) due to curing, and hence a decrease in crack resistance, and (ii) by reducing the polymer fraction in the rubber composition based on an increase in the content of filler and plasticizer, Dimensional stability during processing can be improved, and (iii) Decreasing flame retardancy based on an increase in plasticizer content in the rubber composition by including a flame retardant plasticizer as a plasticizer As a result, it has been found that the present invention can be suppressed, and the present invention has been completed.

That is, the rubber composition for a hose of the present invention contains a rubber component, carbon black, and a plasticizer component, and 100 parts by mass of the rubber component contains 60 parts by mass or more of chloroprene rubber, and 100 parts by mass of the rubber component. More than 50 parts by mass of the carbon black is blended with respect to parts, the plasticizer component contains a flame retardant plasticizer, and 2 parts by mass of the flame retardant plasticizer with respect to 100 parts by mass of the rubber component. It is characterized by being blended in a part or more.

According to the present invention, it is possible to provide a rubber composition for a hose that can satisfy both flexibility after vulcanization and dimensional stability during production extrusion while ensuring flame retardancy. Further, according to the present invention, it is possible to provide a hose that achieves both flexibility and dimensional stability of the product outer diameter while ensuring flame retardancy.

FIG. 1 is a perspective view showing an example of a laminated structure of a hose according to an embodiment of the present invention using the rubber composition for a hose according to an embodiment of the present invention.

In this specification, “flame retardant” means flame retardant in MSHA flame retardant test.

(Rubber composition for hose)
Below, the rubber composition for hoses of this invention is illustrated and explained in detail based on the one embodiment.
The rubber composition for a hose of the present invention includes at least a rubber component, carbon black, and a plasticizer component, and further includes silica and other components as necessary.

<Rubber component>
The rubber component includes at least chloroprene rubber (CR), and further includes styrene-butadiene rubber (SBR), butadiene (BR), and other polymers as necessary.

The rubber composition for a hose of the present invention preferably further contains at least one of styrene-butadiene rubber and butadiene rubber as the rubber component. According to this structure, it can prevent that the abrasion resistance of the rubber composition for hoses falls, or processability (dimensional stability of extrusion, extrusion skin characteristic) can be improved.

<< Chloroprene rubber (CR) >>
The chloroprene rubber (CR) is a homopolymer of a chloroprene monomer (chloroprene polymer) or a mixture of a chloroprene monomer and one or more other monomers copolymerizable therewith (hereinafter referred to as a chloroprene series). A copolymer obtained by polymerizing a monomer (hereinafter referred to as a monomer) (hereinafter referred to as a chloroprene copolymer).

-Classification of chloroprene rubber-
The chloroprene rubber is classified into a sulfur-modified type, a mercaptan-modified type, and a xanthogen-modified type depending on the type of molecular weight regulator.
Any modified type can be used as the chloroprene rubber. However, the sulfur-modified type is inferior in heat resistance of the polymer itself as compared with the mercaptan-modified type and the xanthogen-modified type. It is preferable to use it.

--Sulfur modified type--
In the sulfur-modified type, a polymer obtained by copolymerizing sulfur and a chloroprene monomer or a chloroprene monomer is plasticized with thiuram disulfide and adjusted to a predetermined Mooney viscosity.

--Mercaptan modified type--
The mercaptan-modified type uses alkyl mercaptans such as n-dodecyl mercaptan, tert-dodecyl mercaptan, and octyl mercaptan as molecular weight regulators.

--- Xanthogen-modified type--
The xanthogen-modified type uses an alkyl xanthogen compound as a molecular weight regulator. The alkyl xanthogen compound is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include dimethyl xanthogen disulfide, diethyl xanthogen disulfide, diisopropyl xanthogen disulfide, and diisobutyl xanthogen disulfide. These may be used individually by 1 type and may use 2 or more types together.
The amount of the alkylxanthogen compound used is not particularly limited as long as the molecular weight (or Mooney viscosity) of the chloroprene rubber is appropriate, and the purpose (the structure of the alkyl group and the target molecular weight) is not particularly limited. Depending on the amount of chloroprene monomer or chloroprene monomer, it is preferably 0.05 to 5.0 parts by weight, more preferably 0.3 to 1.0 parts by weight. preferable.

-Content of chloroprene rubber (CR)-
The content of the chloroprene rubber (CR) is not particularly limited as long as it is 60 parts by mass or more in 100 parts by mass of the rubber component, and can be appropriately selected according to the purpose. Preferably, it is 65-80 parts by mass.
When the content of the chloroprene rubber (CR) is less than 60 parts by mass in 100 parts by mass of the rubber component, flame retardancy cannot be ensured. On the other hand, when the content of the chloroprene rubber (CR) is within the above preferable range, it is advantageous in terms of flame retardancy, processability (stand stability), oil resistance, and weather resistance, and is more preferable than the above range. It is further advantageous to be within.

<< Styrene-Butadiene Rubber (SBR) >>
The above styrene-butadiene rubber (SBR) can be copolymerized with styrene monomer and butadiene monomer (styrene-butadiene copolymer), or with styrene monomer and butadiene monomer. A copolymer (hereinafter referred to as a styrene-butadiene copolymer) obtained by polymerizing a mixture with one or more other monomers (hereinafter referred to as a styrene-butadiene monomer). .
By blending styrene-butadiene rubber (SBR), it is possible to prevent the wear resistance from deteriorating and to improve processability (extrusion dimensional stability, extrusion skin characteristics).

-Monomer copolymerizable with styrene monomer and butadiene monomer-
The monomer copolymerizable with the styrene monomer and butadiene monomer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 2-methyl-1,3-butadiene, 2 Conjugated diene monomers having 5 to 8 carbon atoms such as 1,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene; p-methylstyrene, α-methylstyrene, vinylnaphthalene, etc. Aromatic vinyl monomer; and the like. These may be used individually by 1 type and may use 2 or more types together.

-Styrene-styrene content of butadiene rubber (SBR)-
The styrene content of the styrene-butadiene rubber (SBR) is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 20 to 45% by mass, more preferably 20 to 35% by mass.
When the styrene content of the styrene-butadiene rubber (SBR) is 20% by mass or more, the effect of improving the workability is sufficiently obtained, and when it is 45% by mass or less, the effect of preventing a decrease in wear resistance is sufficient. Is obtained. On the other hand, if the styrene content of the styrene-butadiene rubber (SBR) is within the more preferable range, it is more advantageous in terms of workability and wear resistance.

-Styrene-butadiene rubber (SBR) content-
The content of the styrene-butadiene rubber (SBR) is not particularly limited as long as it is 40 parts by mass or less in 100 parts by mass of the rubber component, and can be appropriately selected according to the purpose. Part by mass is preferred.
When the content of the styrene-butadiene rubber (SBR) exceeds 40 parts by mass in 100 parts by mass of the rubber component, the ratio of chloroprene rubber (CR) decreases, so that the flame retardancy decreases. On the other hand, when the content of the styrene-butadiene rubber (SBR) is within the above preferable range, it is more advantageous in terms of flame retardancy, wear resistance, and workability (extrusion dimensional stability, extrusion skin characteristics). It is.

<< Butadiene rubber (BR) >>
The butadiene rubber (BR) is a homopolymer of a butadiene monomer (butadiene polymer), or a mixture of a butadiene monomer and one or more other monomers copolymerizable therewith (hereinafter referred to as a butadiene type). A copolymer obtained by polymerizing a monomer (hereinafter referred to as a butadiene copolymer). The butadiene rubber (BR) may be end-modified.
Abrasion resistance can be improved by mix | blending the said butadiene rubber (BR).

-Cis-1,4 bond amount of butadiene rubber (BR)-
The amount of cis-1,4 bonds in the butadiene rubber (BR) is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 90% or more, more preferably 93% or more, and 95% or more. Is particularly preferred.
If the amount of cis-1,4 bonds is less than 90% and is unmodified, wear resistance may not be sufficiently improved. On the other hand, even if the amount of cis-1,4 bonds is within the more preferred range or less than 90%, terminal-modified BR is advantageous in terms of wear resistance, and is within the particularly preferred range. Further advantageous.
The amount of cis-1,4 bond can be measured using ¹ H-NMR, ¹³ C-NMR, FT-IR, or the like.

-Butadiene rubber (BR) content-
The content of the butadiene rubber (BR) is not particularly limited as long as it is 40 parts by mass or less in 100 parts by mass of the rubber component, and can be appropriately selected according to the purpose. Is preferred.
When the content of the butadiene rubber (BR) exceeds 40 parts by mass in 100 parts by mass of the rubber component, the ratio of the chloroprene rubber (CR) is decreased, so that the flame retardancy is decreased. On the other hand, when the content of the butadiene rubber (BR) is within the preferable range, it is more advantageous in terms of flame retardancy and wear resistance.

<< other polymers >>
There is no restriction | limiting in particular as said other polymer, According to the objective, it can select suitably, For example, natural rubber (NR), butyl rubber (IIR), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CPE) ), Acrylonitrile butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber (H-NBR), acrylic rubber (ACM), ethylene-propylene rubber (EPDM), epichlorohydrin rubber (CO), hydrin rubber (ECO), silicone rubber (Q) ), Fluoro rubber (FKM), polyvinyl chloride (PVC), blend rubber (NV) of polyvinyl chloride (PVC) and acrylonitrile butadiene rubber (NBR) (corresponds to "mixture of polyvinyl chloride and acrylonitrile butadiene rubber") ), Chlorinated natural rubber, etc. It is below. These may be used individually by 1 type and may use 2 or more types together.
Among these, CSM and CPE are preferable in terms of flame retardancy.

<Carbon black>
By blending the carbon black with the rubber component, it is possible to ensure reinforcement and flame retardancy.
There is no restriction | limiting in particular as said carbon black, According to the objective, it can select suitably, For example, FEF class, HAF class, ISAF class, SAF class, GPF class, SRF class, FT class, MT class, etc. Things. These may be used individually by 1 type and may use 2 or more types together.
Among these, from the viewpoint of the balance of wear resistance, initial elongation (crack resistance), and workability, the FEF class (iodine adsorption 40 to 60 mg / g (g / kg), DBP oil absorption 100 to 130 mL / 100 g). (100 × 10 ⁻⁵ m ³ / kg to 130 × 10 ⁻⁵ m ³ / kg) is desirable.

The iodine adsorption amount of the carbon black is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 20 to 160 mg / g, and more preferably 40 to 60 mg / g.
When the amount of iodine adsorbed on the carbon black is within the above preferable range, it is advantageous in terms of the balance of wear resistance, workability, and elongation after heat aging, and more preferable when within the above preferable range. is there.

The DBP oil absorption amount of the carbon black is not particularly limited and may be appropriately selected depending on the intended purpose. It is preferably 30 to 150 mL / 100 g, more preferably 100 to 130 mL / 100 g.
When the DBP oil absorption amount of the carbon black is within the above preferred range, it is advantageous in terms of the balance of wear resistance, workability, and elongation after heat aging, and more advantageously within the above preferred range. is there.

The carbon black preferably has an iodine adsorption of 20 to 160 mg / g, a DBP oil absorption of 30 to 150 mL / 100 g, an iodine adsorption of 30 to 100 mg / g, and a DBP oil absorption of 50 to It is more preferably 130 mL / 100 g, an iodine adsorption amount of 40 to 60 mg / g, and a DBP oil absorption amount of 100 to 130 mL / 100 g are particularly preferable. According to this structure, the abrasion resistance and workability of the rubber composition for hoses can be ensured.
When the iodine adsorption amount and DBP oil absorption amount of the carbon black are within the above preferred ranges, it is advantageous in terms of the balance of wear resistance, workability, and elongation after heat aging, and within the above preferred ranges, or particularly It is further advantageous to be within the preferred range.
In addition, the measuring method of iodine adsorption amount and the measuring method of DBP oil absorption amount are methods according to JIS K 6217.

-Carbon black content-
The compounding amount of the carbon black is not particularly limited as long as it exceeds 50 parts by mass with respect to 100 parts by mass of the rubber component, and can be appropriately selected according to the purpose. The amount is preferably 65 to 75 parts by mass.
When the blending amount of the carbon black is 50 parts by mass or less with respect to 100 parts by mass of the rubber component, dimensional stability at the time of extrusion cannot be ensured. On the other hand, when the blending amount of carbon black is within the above preferable range, it is advantageous in terms of flame retardancy and dimensional stability.

In the rubber composition for a hose of the present invention, it is preferable that 65 parts by mass or more of carbon black is blended with 100 parts by mass of the rubber component. According to this structure, the more outstanding flame retardance and dimensional stability can be expressed.

<Silica>
By blending the above silica with the above rubber component, flame retardancy is improved (especially afterglow disappearance time is shortened), while workability (extrusion dimensional stability, extruded skin characteristics) and wear resistance are maintained. can do.
The nitrogen adsorption specific surface area of the silica (N ₂ SA), is not particularly limited and may be appropriately selected depending on the intended purpose, preferably 70 ~ 300m ² / g, more preferably 100 ~ 280m ² / g 150 to 250 m ² / g is particularly preferable.
When the nitrogen adsorption specific surface area (N ₂ SA) of the silica is 70 m ² / g or more, the effect of improving flame retardancy and wear resistance can be sufficiently obtained, and it is 300 m ² / g or less. The effect of improving dispersibility and workability can be sufficiently obtained. On the other hand, when the nitrogen adsorption specific surface area (N ₂ SA) of the silica is within the above preferable range, it is advantageous in terms of the balance of flame retardancy, wear resistance, dispersibility, and workability, and the above is particularly preferable. Within the range, it is further advantageous.

-Blending amount of silica-
The compounding amount of the silica is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 5 to 25 parts by mass, more preferably 15 to 25 parts by mass with respect to 100 parts by mass of the rubber component. preferable.
When the amount of silica is 5 parts by mass or more, flame retardancy can be prevented from decreasing (afterglow disappearance time becomes long), and when it is 25 parts by mass or less, it becomes too hard. Can be prevented. On the other hand, when the blending amount of the silica is in a more preferable range, it is advantageous in terms of processability (extruded dimensional stability, extruded skin characteristics) in the blending ratio of each component of the present application.

In the rubber composition for a hose of the present invention, it is preferable that 5 to 25 parts by mass of silica is further blended with 100 parts by mass of the rubber component. According to this configuration, flame retardancy can be improved (particularly, the afterglow disappearance time can be shortened), and workability (extruded dimensional stability, extruded skin characteristics) can be improved.

<Plasticizer component>
By blending the plasticizer component with the rubber component, the initial elongation (flexibility and consequently crack resistance) can be improved.
The plasticizer component contains at least a flame retardant plasticizer, and, if necessary, other paraffinic oils such as spindle oil, aroma oils such as aroma oil, naphthenic oils, ester oils, other Contains plasticizer.

<< Flame-retardant plasticizer >>
The flame retardant plasticizer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include chlorinated aliphatic compounds such as chlorinated paraffin; halogenated phosphate ester compounds and non-halogenated phosphorus. Acid ester compounds; ester compounds; silicone compounds; and the like. These may be used individually by 1 type and may use 2 or more types together.
There is no restriction | limiting in particular as a specific example of the said chlorinated paraffin, According to the objective, it can select suitably, For example, chlorinated paraffin (liquid) with a chlorination rate of 43%, chlorination paraffin with a chlorination rate of 50% (Liquid).
Specific examples of the halogen phosphate compound are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include trischloropropyl phosphate, a condensate of trischloropropyl phosphate and dialkylene glycol. Can be mentioned.
Specific examples of the non-halogen phosphate ester compound are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include triphenyl phosphate and tricresyl phosphate.
There is no restriction | limiting in particular as a specific example of the said silicone type compound, According to the objective, it can select suitably, For example, polydialkylsiloxane etc. are mentioned.

In the rubber composition for a hose of the present invention, the flame retardant plasticizer is preferably at least one of a chlorinated aliphatic compound and a phosphate ester compound, and the flame retardant plasticizer is a chlorinated paraffin. And at least one of a halogen-based phosphate ester-based compound is more preferable. According to this configuration, it is possible to achieve both flexibility and dimensional stability while ensuring the flame retardancy of the rubber composition for hoses more reliably.

-Amount of flame retardant plasticizer-
The amount of the flame retardant plasticizer is not particularly limited as long as it is 2 parts by mass or more with respect to 100 parts by mass of the rubber component, and can be appropriately selected according to the purpose. The amount is preferably 2 to 25 parts by mass with respect to 100 parts by mass.
When the blending amount of the flame retardant plasticizer is less than 2 parts by mass with respect to 100 parts by mass of the rubber component, for example, sufficient flame retardancy is obtained when the amount of chloroprene rubber or carbon black is relatively small. I can't. On the other hand, when the blending amount of the flame retardant plasticizer is within the above preferable range, it is advantageous in terms of a balance between flame retardancy, initial elongation (flexibility, and crack resistance) and workability.

In the rubber composition for a hose of the present invention, it is preferable that 2 to 25 parts by mass of the flame retardant plasticizer is blended with 100 parts by mass of the rubber component. According to this structure, dimensional stability can be improved more reliably, ensuring the flame retardance of the rubber composition for hoses.

<Other ingredients>
In addition to carbon black and silica, inorganic fillers such as talc, clay and calcium carbonate; vulcanizing agents such as peroxide vulcanizing agents; vulcanization accelerators; zinc oxide (zinc white), Vulcanization accelerators such as stearic acid; vulcanization retarder; anti-aging agent; wax; anti-scorch agent; softener; silane coupling agent, organic acid metal salt (organic acid cobalt etc.), resorcin, hexamethylenetetramine, Adhesives such as melamine resins; metal compounds such as magnesium oxide, calcium oxide, calcium carbonate, aluminum hydroxide, and magnesium hydroxide; Can be appropriately selected and blended. As these compounding agents, commercially available products can be suitably used.

The above rubber composition is blended with the above-mentioned various compounding agents, which are appropriately selected as necessary, in an essential component comprising a rubber component, carbon black, and a plasticizer component, and kneaded, heated, extruded, etc. Can be manufactured.

(hose)
The hose of the present invention has at least a rubber layer, and further includes layers other than the rubber layer and other members as necessary.

The hose of the present invention has a rubber layer using the rubber composition for a hose of the present invention.
According to the hose of the present invention, it is possible to achieve both flexibility and dimensional stability during production extrusion while ensuring flame retardancy.

-Rubber layer-
The rubber layer is composed of the rubber composition for hoses of the present invention. There is no restriction | limiting in particular as a site | part in the hose which applies this rubber layer, According to the objective, it can select suitably, For example, the intermediate | middle rubber layer which does not form the inner and outer surface of a hose, and / or the outer surface of a hose is formed. The outer surface rubber layer (outer rubber layer) and the like are particularly preferable. The outer surface rubber layer is preferably the rubber layer.
There is no restriction | limiting in particular as a shape, a structure, and a magnitude | size of the said outer surface rubber layer, According to the objective, it can select suitably.
The thickness of the outer rubber layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.3 to 3.5 mm, more preferably 0.7 to 3.2 mm, and 1.0 Particularly preferred is ˜3.0 mm.
If the thickness of the outer rubber layer is 0.3 mm or more, it can be prevented from wearing and reaching an early life, and if it is 3.5 mm or less, the flame retardancy decreases due to an increase in the amount of combustion components. Can be prevented, or inferior in terms of flexibility, weight reduction, and space saving as a hose. On the other hand, when the thickness of the outer rubber layer is within the more preferable range, it is advantageous in terms of flame retardancy and wear life, and when the thickness is within the particularly preferable range, it is more advantageous.

An example of a laminated structure of a hose according to an embodiment of the present invention is shown in FIG. In FIG. 1, a hose 1 is a hydraulic hose, an inner rubber layer 10, reinforcing

layers

12, 14, 16, 18 having brass plating wires, intermediate rubber layers 11, 13, 15, 17, and outer rubber layers. 19.
The rubber composition for a hose of the present invention is suitable for use in at least the outer rubber layer 19, and is used for all or a part of the intermediate rubber layers 11, 13, 15, 17 and the outer rubber layer 19. You can also.

The hose has an inner rubber layer 10 from the inner side, four reinforcing

layers

12, 14, 16, 18 and intermediate rubber layers 11, 13, 15, 17, and an outer rubber layer 19, respectively. However, the present invention is not limited to this. For example, a three-layer structure in which an inner rubber layer, a reinforcing layer, and an outer rubber layer are sequentially laminated may be used. It can be appropriately selected depending on the case. Moreover, it is not necessary for all the reinforcing layers to be formed of a brass plating wire, and a reinforcing layer partially formed of organic fibers can also be used. Alternatively, a hose in which a resin layer such as ultra high molecular weight polyethylene is disposed on the outermost layer to improve wear resistance may be used.

<Method of manufacturing hose>
As a method for producing the hose of the present invention, for example, as follows, an inner tube extrusion step, a braiding step, a jacket extrusion step, a resin mold coating step, a vulcanization step, and a resin mold peeling step And a mandrel extraction step, and a method including other steps appropriately selected as necessary.
The hose having the structure shown in FIG. 1 will be described as an example. First, a rubber composition for the inner rubber layer 10 is extruded on the outer side of a core body (mandrel) having a diameter approximately equal to the inner diameter of the hose to cover the mandrel. Then, the inner rubber layer 10 is formed (inner tube extrusion step). In addition, on the inner tube | pipe rubber layer 10, the layer formed with an organic fiber can also be introduce | transduced as a wire disorder prevention at the time of wire braiding. Next, a predetermined number of brass plating wires are knitted outside the inner rubber layer 10 formed by the inner tube extrusion step to form a reinforcing layer 12 (knitting step), and the hose of the present invention is formed inside the reinforcing layer 12. The intermediate rubber layer 11 is formed by inserting and forming a sheet of the rubber composition. This is repeated a plurality of times, and the reinforcing

layers

14, 16, 18 and the intermediate rubber layers 13, 15, 17 are sequentially laminated to extrude the outer surface rubber layer 19 made of the rubber composition for hose of the present invention (outer extrusion process) ). Further, the outer surface of the outer rubber layer 19 formed in the outer shell extrusion step is appropriately coated with a suitable resin (resin mold coating step), and vulcanized under predetermined conditions (vulcanization step). After vulcanization, the coating resin is peeled off (resin mold peeling step), and the mandrel is removed (mandrel extraction step), whereby intermediate rubber layers 11, 13, 15 are interposed between the inner rubber layer 10 and the outer rubber layer 19. 17 and the reinforcing

layer

12, 14, 16, 18 are obtained.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and can be appropriately changed without departing from the scope of the present invention.

First, the polymer and rubber composition described below were prepared. The evaluation method of a rubber composition is shown below. The unit of the values described as the blending amounts in Tables 1 to 6 is parts by mass. In Tables 1 to 6, the rubber compositions of Examples and Comparative Examples have (i) 5 parts by mass of zinc oxide, (ii) 4 parts by mass of magnesium oxide, and (iii) with respect to 100 parts by mass of the rubber component. ) Wax (OZOACE0017, Nippon Seiwa Co., Ltd.) 2 parts by mass, (iv) Anti-aging agent (ANTIGENE 6C, Sumitomo Chemical Co., Ltd.) 3 parts by mass, (v) Cobalt stearate 2 parts by mass, (vi) 1 part by mass of sulfur and (vii) 2 parts by mass of vulcanization accelerator (NS) are further contained.

<Evaluation method of rubber composition>
(1) Flame resistance (flame disappearance time)
The flame retardancy (flame extinction time) was evaluated based on the flame retardancy (flame extinction time) evaluation of MSHA standard (American Mine Safety Standard) ASTP5007. In addition, the thickness of the evaluation sample obtained by press-vulcanizing the rubber sheet with a mold at 150 ° C. for 60 minutes and cutting out to a predetermined dimension was 3 mm.
The obtained evaluation results are shown in Tables 1-6. Here, as the flame disappearance time, the smaller the numerical value, the better the flame retardancy.
The evaluation criteria are as follows.
◎: 0 seconds to 10 seconds ○: 10 seconds to 30 seconds △: 30 seconds to 60 seconds or less ×: 60 seconds or more

(2) Dimensional stability (mill shrinkage test)
The dimensional stability (mill shrinkage test) was measured by the following procedure.
A 6-inch roll temperature-controlled at 60 ° C. is used, and wound for 2 minutes at a roll gap of 2 mm and 20 rpm, and heated. The roll was stopped, and the rubber wound around the roll was die-cut with a 5 cm square mold. After being allowed to stand for 1 hour, the contraction rate (%) was calculated by dividing the length from 5 cm by 5 cm.
The obtained evaluation results are shown in Tables 1-6.
The evaluation criteria are as follows.
◎: 10% or less ○: Over 10% over 20% △: Over 20% over 30% ×: Over 30%

(3) Initial elongation (initial Eb (%))
The initial elongation (initial Eb (%)) is measured by No. 3 dumbbell shape according to JIS K 6251, and the elongation at break when the test piece is cut (elongation at break) is a ratio (% ).
The measurement results obtained are shown in Tables 1-6. Here, as the initial elongation (initial Eb (%)), a larger value is better because flexibility (crack resistance) can be improved. The acceptance criterion is 300% or more.

In Tables 1 to 6, * 1 to * 12 indicate the following.
* 1: Chloroprene rubber (CR): manufactured by Denki Kagaku Kogyo, electrified chloroprene “M40”
* 2: Styrene-butadiene rubber (SBR): JSR, “JSR1500”
* 2-2: Butadiene rubber (BR): “BR01” manufactured by JSR (cis-1,4 bond content: 95%)
* 3: FEF carbon black: manufactured by Asahi Carbon, "Asahi # 65": iodine adsorption amount 43 mg / g, DBP oil absorption amount 121 mL / 100 g
* 4: FT carbon black: Asahi Carbon, “Asahi Thermal”: iodine adsorption 27 mg / g, DBP oil absorption 28 mL / 100 g
* 5: HAF carbon black: manufactured by Asahi Carbon, “Asahi # 70”: iodine adsorption amount 82 mg / g, DBP oil absorption amount 102 L / 100 g
* 6: ISAF carbon black: manufactured by Tokai Carbon Co., Ltd., “Seast 6”: iodine adsorption amount 120 mg / g, DBP oil absorption amount 115 mL / 100 g
* 7: Silica: “Nipsil AQ” manufactured by Tosoh Silica
* 8: Spindle oil: “Super Oil Y22” manufactured by JX Nippon Oil & Energy
* 9: Aroma oil: “Diana Process Oil AH-58” manufactured by Idemitsu Kosan
* 10: Chlorinated paraffin (flame retardant plasticizer): Ajinomoto Fine-Techno "Empara K-43": Chlorination rate 43%
* 11: Non-halogen phosphate (flame retardant plasticizer): “TCP” manufactured by Hodogaya Chemical
* 12: Halogen-based phosphate ester (flame retardant plasticizer): “DAIGUARD-540” manufactured by Daihachi Chemical

From Tables 1 to 6, 100 parts by mass of rubber component contains 60 parts by mass or more of chloroprene rubber, and more than 50 parts by mass of carbon black is compounded with respect to 100 parts by mass of rubber component. In addition, Examples 1 to 34 containing 2 parts by mass or more of a flame retardant plasticizer as a plasticizer component are more effective than the Comparative Examples 1 to 14 that do not satisfy the above requirements. It can be seen that both the flexibility after vulcanization and the dimensional stability during production extrusion can be achieved while ensuring.

The rubber composition for a hose of the present invention can be suitably used, for example, for an intermediate rubber layer and / or an outer rubber layer of a hydraulic hose of a hydraulic excavator used in a coal mine or a mine.

1: hose, 10: inner rubber layer, 11, 13, 15, 17: intermediate rubber layer, 12, 14, 16, 18: reinforcing layer, 19: outer rubber layer

Claims

Including a rubber component, carbon black, and a plasticizer component;
In 100 parts by mass of the rubber component, 60 parts by mass or more of chloroprene rubber is contained,
More than 50 parts by mass of the carbon black is blended with respect to 100 parts by mass of the rubber component,
The rubber composition for hoses, wherein the plasticizer component includes a flame retardant plasticizer, and 2 parts by mass or more of the flame retardant plasticizer is blended with 100 parts by mass of the rubber component.
The rubber composition for a hose according to claim 1, wherein the flame retardant plasticizer is at least one of a chlorine aliphatic compound and a phosphate ester compound.
The rubber composition for a hose according to claim 2, wherein the flame retardant plasticizer is at least one of a chlorinated paraffin and a halogen phosphate compound.
The rubber composition for a hose according to any one of claims 1 to 3, wherein 2 to 25 parts by mass of the flame retardant plasticizer is blended with 100 parts by mass of the rubber component.
The rubber composition for a hose according to any one of claims 1 to 4, wherein 65 parts by mass or more of carbon black is blended with 100 parts by mass of the rubber component.
6. The rubber composition for a hose according to claim 1, wherein the carbon black has an iodine adsorption of 20 to 160 mg / g and a DBP oil absorption of 30 to 150 mL / 100 g.
The rubber composition for a hose according to claim 6, wherein the carbon black has an iodine adsorption of 40 to 60 mg / g and a DBP oil absorption of 100 to 130 mL / 100 g.
The rubber composition for a hose according to any one of claims 1 to 7, further comprising at least one of styrene-butadiene rubber and butadiene rubber as the rubber component.
The rubber composition for hoses according to any one of claims 1 to 8, wherein 5 to 25 parts by mass of silica is further blended with 100 parts by mass of the rubber component.
A hose comprising a rubber layer using the rubber composition for a hose according to any one of claims 1 to 9.